Method of recovering lost circulation in drilling wells



June 16, 1953 A. ARMENTROUT 2,642,268

METHOD OF RECOVERING LOST CIRCULATION IN DRILLING WELLS Filed Feb. 28, 1948 IN V EN TOR.

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HTTOENEVS Patented June 16, 1953 UNITED STATES TENT OFFICE METHOD OF RECOVERING LOST CIRCU- LATION IN DRILLING WELLS 4 Claims.

This invention relates to a means and method of recovering lost circulation in the course of drilling wells.

In the course of drilling wells such as oil wells by the rotary well drilling apparatus, circulation fluid or mud is pumped down through the drill pipe and discharged at or near the bit at the bottom thereof. The circulation fluid then normally rises within the well bore around the drill pipe carrying with it the cuttings, and on issuing from the well bore at the surface the circulation fluid is conducted to a sump where the cuttings may settle out. This circulation fluid may then be returned to the mud pumps and forced thereby down through the drill pipe, completing a cycle of its flow.

In the course of drilling many wells in this manner porous formations, earth cracks and water sands are penetrated by the well bore so that I it not infrequently occurs that the circulation fluid which is discharged at or near the bit, on rising in the Well bore to the porous formations, cracks or water sands, escapes therethrough and. consequently does not return to the surface and to the sump. When this occurs circulation is said to become lost and steps are then taken to endeavor to plug or seal the water sands, porous formations or earth cracks to prevent the escape of circulation fluid therethrough. Many types of plugging materials have heretofore been used for this purpose including bentonite, quick setting cements, plasters and like materials that are adapted to set up and harden on coming in contact with the circulation fluid. The bentonite performs its plugging action largely by its ability to swell in the presence of water. The practice heretofore has generally been to merely introduce such swellable or settable materials into the circulation fluid so that they will be carried thereby down through the drill pipe and be discharged into the well bore. These materials will also be carried to the porous formations, earth cracks or water sands where the circulation fluid is lost and sometimes coagulate and collect at these localities and harden so as to seal them off against continued escape of circulation fluid therethrough.

An important objection to this procedure resides in the fact that the materials used being designed to commence to set up or harden on coming in contact with the circulation fluid commence their setting up or hardening action immediately on being introduced into the fluid. However, in the case of deep Wells especially, some considerable lapse of time must take place for the introduced sealing material to be pumped down through the drill pipe, discharged at or near the bit, and rise to the locality where the seal is to be effected. This lapse of time frequently is so great that by the time the sealing material has reached the locality to be sealed off it has lost its efliciency, or its ability to set up and harden has been greatly reduced.

An object of the present invention is to provide a method and apparatus whereby finely divided sealing materials such as bentonite, quick setting cements, plasters and the like may be introduced into the circulation fluid in a compacted condition and preferably in the form of small lumps. In this manner the wetting or penetration of the interior of the lumps will be somewhat postponed or delayed affording an adequate opportunity to pump the lumps into the well and either approach or reach the locality to be sealed off before the interior of the lumps have become wetted thereby. Consequently, that material that is disposed on the interior of the lumps will be delivered to the locality to be sealed in a comparatively fresh condition and on being wetted eventually by the circulation fluid it may be capable of swelling or setting up and hardening to form an adequate seal. The material on the surfaces of the lumps may, of course, become devitalized or even rendered non-settable by reason of its prolonged contact with the circulation fluid while it is being pumped into place and, if so, such material may pass on with the circulation fluid that is being lost. However, the material within the lumps being delivered to the locality to be sealed in a vitalized condition will, on being wetted by the circulation fluid, be capable of setting up and forming a leak-proof seal.

Another object of the invention is to provide a method and apparatus for accomplishing the above results which can be used in the course of drilling so that it is not necessary, in recovering the lost circulation, to discontinue or postpone drilling operations.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure l is a schematic view illustrating a well as being drilled by the rotary method of drilling and illustrating apparatus embodying the present invention as having been incorporated therein; and

Fig. 2 is a view in side elevation, parts being ing a kelly 13 mounted at its upper end which extends through the contentional rotary table i l. l indicates the rotary hose that receives mud or circulation fluid from a mud pump it and conducts it to a swivel case ll at the top. of

the kelly so as to be forced downwardly through the drill pipe 12 for discharge through circulation ports it in the bit H. Inthe normal course.

of operation the discharged circulation fluid rises in the well bore id and is conducted therefrom to a sump from which the circulation fluid may be returned to the pump it. However, in the situation illustrated the well bore it may be assumed to have penetrated a highly porous stratum, water sand, or to have traversed an earth crack indicated at is so that the circulation fluid instead of returning to through the stratum and becomes lost.

In accordance with thepresent invention a suitable container Efi is provided which preferably has a'conical bottom ill in which there is a port This port leads into a conduit 23 a portion of which provides a cylinder for a reciprocating piston 25. The piston 25 can be reciprocate-d any suitable-manner such as by a connecting rod 26 which is connected to the wrist ton 25 and to a crank ii that can be rotated.

in any suitable manner such as by a motor The conduit 23 leads through a valve to a manifold that conducts the circulation fluid from the pump id to the rotary hose 2%. At the top of the container it there isdisposed an inlet valve 3% above which there may be a hopper t2 andnear the bottom of the container there is preferably provided a. drain equipped with a valve Adjacent the container so there a suitable reservoir or tank 35 that is connected to the container 263 such as indicated at 38. This tank has its lower end likewise connected to the manifold 30 by means of a valved conduit 3? and preferably has a valve controlled drainat 38.

In using the above described apparatus the following operations may be formed-.- Any mate rial, such as bentonite, cement, plaster or Cal- Seal, adapted to set up or harden on coming in contact with the circulation fluid, may be employed and may be positioned in a finely divided condition in the hopper 32. On opening valve 3! this material is allowed to enter the container 2%? after which the-valve 32 is closed. Valve. 31 may then be opened allowing circulation fluid to enter the tank 35 as indicated in Fig. 2. This compresses the air in the top of the tank to the the surface escapes ie pis-- pressure existing in the manifold 36 and the pressure is, of course, transmitted through 36- to the interior of the container 20. The motor 28 may then be started to reciprocate the piston 25 and the valve 29 opened. The piston 25 is so arranged that as it reciprocates it will expose or open the port 22 to permit successive incremerits of the material to descend from the con tainer 20 into the conduit 23. On forward strokes of the piston these successive increments will be highly compressed by the piston against the pressure of the circulationfluid in the manifold 39 and in the conduit 23 and will be forced through the conduit into the manifold. The valve 28 which may be in the form of a rotary plug type it is in effect compacted so. that as it issues from 10 the conduit 23 into the manifold 36 it is somewhat in the nature of a solid.- These solids as they are forced from the conduit 23 into the manifold 39 will, of course, break off from time to. time by the flowing circulation fluid, but will to a large extent remain in their compacted condition or in the form of lumps. These lumps will be carried by the circulation fluid into the rotary hose l5, down through the drill pipe 52 and be discharged through the ports is and eventually rise to the location l9 that is to be sealed. The

compacted or lumpy condition of the sealing. ma

terial prevents immediate wetting of the interior of the lumps by thecirculation fluid and although the external surfaces of the lumps may be immediately wetted within the manifold the in teriors of the lumps will be kept comparatively dry while the lumps are being pumped to the location i'ii. Consequently that portion of the material that is within the lumps will reach or approach the location it in. a comparatively fresh or vitalized condition and as soon as the circulation fluid penetrates the lumps to wet the interiors thereof this fresh sealing material will then be wetted and will be in a condition to set up and form a hard seal.

lvlost materials used for this purpose are designed to set up or harden on merely contacting with the water constituent of the circulation fluid.

It will, of course, be appreciated, however, that materials designed to set up or harden in coming in contact with an acid or alkali can be employed and the necessary acid or alkali can be introduced into the circulation fluid.

The pressure tank 35 is merely used as a means for equalizing the pressure in the top of container 2b with the pressure that may exist in the conduit 23 so that the. sealing material in the tank may readily flow by successive increments from the tank into the conduit 23 whenever the port 22 is opened by the piston 25.

When suflicient sealing material to effect a seal is pumped into the well, any remaining sealing material in the tank 2E1 can be drained therefromthrough the drain 3-3 on, opening valve 34. Likewise if any liquid in the pressure tank 35 should be inadvertently or accidentally driven over through 36 into container this can be withdrawn through the drain 33 so that the sealing material will not set up within the container 29. As the sealing material is feel out of container 20 into conduit the level of liquid in the pressure tank 35 will, of course, rise. This may be lowered or the pressure tank may be emptied at the conclusion of the operation by closing valve 3! and opening the drain valve 38. It will be appreciated, of course, that in using the improved apparatus and method of recovering lost circulation in the well it is unnecessary to interrupt or discontinue drilling operations and if the manifold 36 is initially equipped with the valves 29 and 3'! the apparatus may be connected thereto and disconnected therefrom while drilling operations are continuing.

Itis, of course, desirable to have the lumps of sufliciently small size so that they may readily pass through the circulation ports in the bit. To this end it is desirable to have the lumps in the neighborhood of 4; in diameter by /2" to 1" in length so that by using a bit having large circulation holes these lumps may readily pass therethrough. To this end it may be desirable to install in the manifold 30 a deflector 39 which will cause the lumps of the extruded sealing material to break off before they have exceeded a predetermined maximum length.

From the above described method and apparatus it will be appreciated that this invention enables finely divided sealing material that is adapted to set up or harden on coming in contact with the circulation fluid to be delivered at or near the location" to be sealed off in a relatively fresh or vitalized condition and that its effectiveness to form a hard seal is not lost or reduced as in the practices heretofore employed wherein the finely divided sealing material was delivered in a finely divided condition into the path of the circulation fluid at the surface and consequently immediately began to set up.

Various changes may be made in the details of construction without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. The method of recovering lost circulation in drilling wells in which there is a drilling string and a bit attached thereto which comprises pressure compacting into lumps of as large a size as may be reasonably expected to pass through the circulation ports in the bit a finely divided material which will commence setting up on contacting the circulation fluid and feeding the lumps into the circulation fluid forced into the well whereby due to the compacted nature of the material penetration of the circulation fluid to the interiors of the lumps will be delayed until the material approaches or has reached the location it is desired to seal in order to recover circulation.

2. The method of recovering lost circulation in drilling wells in which there is a drilling string and a bit attached thereto which comprises feeding into circulation fluid as it is forced into the well pressure compacted lumps of such a size as may be reasonably expected to pass through the circulation ports of the bit of finely divided material Which will commence setting up on contacting the circulation fluid whereby 'due to the com- 6 pacted nature of the lumps setting up of the material on the interiors of the lumps will be delayed until the material approaches or has reached the location it is desired to seal in order to recover circulation.

3. The method of recovering lost circulation in drilling wells in which there is a drilling string and a bit attached thereto which comprises feeding into circulation fluid as it is forced into the well pressure-compacted lumps as large as may be reasonably expected to pass through the circulation ports of the bit of finely divided sealing material which will commence setting up on contacting this circulation fluid whereby due to the compacted nature of the lumps setting up of the material on the'interiors of the lumps will be delayed until the material approaches or has reached the location it is desired to seal.

4. The method of recovering lost circulation in drilling wells in which there is a drilling string and a bit attached thereto which comprises compressing against the pressure of circulation fluid forced into the well a finely divided material which commences fitting on contacting the circulation fluid, and forcing the compressed material into the stream of circulation fiuid so that it will be supplied thereto in lumpy masses of as large a size as may be reasonably expected to pass through the circulation ports of the bit whereby the material may be carried toward or to the location to be sealed before the interiors of the masses have been completely wetted by the circulation fluid and consequently setting of the entire material will be delayed until the locality to be sealed is at least approached.

ARTHUR L. ARMIENTROUT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,265,614 Conant May 7, 1918 1,761,875 Cordell et al. June 3, 1930 1,885,081 Clapp Oct. 25, 1932 1,893,738 Goodman Jan. 10, 1933 1,960,435 Dudley May 29, 1934 2,058,309 Haering Oct. 20, 1936 2,064,936 McQuiston Dec. 22, 1936 2,191,652 Hamilton, Jr Feb. 27, 1940 2,217,926 Van Campen Oct. 15, 1940 2,338,174 Garrison Jan. 4, 1944 2,417,307 Larsen Mar. 11, 1947 

